This invention relates to apparatus for accessing telephone cable pairs and, in particular, to apparatus for accessing subscriber cable pairs and central office cable pairs at a telephone central office.
Many telephone central offices employ so-called "main distributing frames" as wiring support structures for interconnecting the subscriber cable pairs incoming to the central office and the central office cable pairs connected to the central office switching equipment. Typically, main distributing frames in use today comprise groups of vertically and horizontally oriented terminal blocks. The vertical terminal blocks interconnect the incoming subscriber cable pairs (Tip and Ring) with the associated central office cable pairs. The latter, in turn, also connect to the horizontal terminal blocks. So called cross-connects then connect the horizontal terminal blocks to the telephone switching equipment. As a result, a link is established between the subscriber cable pairs and the switching equipment.
The vertical terminal blocks of the main distributing frame generally contain groups of sockets arranged in rows and columns. For example, there may be five groups in a row and twenty groups in a column to provide one hundred groups of sockets.
In each group of sockets, a first pair of sockets connect with a subscriber cable pair and a second group of sockets connect with a central office cable pair. A further socket connects with ground. Each socket group then receives a lightning or surge protector module. The latter protectively interconnects the first and second socket pairs and, hence, the associated subscriber and central office cable pairs.
Because of the many cable pairs handled by a main distributing frame and its terminal blocks there is a dense packing of blocks and cables. This makes it extremely difficult to gain access to the interconnected cable pairs for testing by telephone personnel. Also, since the cables in many central offices have been in place for many years, there is a likelihood that they are brittle and, hence, may require care in handling during any testing procedure.
Present day devices used to access and test cable pairs at the main distributing frame generally use a fragile test cord which has a short lifespan and, thus, must be frequently replaced. This increases the cost of the testing procedure. An alternative more bulky test cord may also be used, but it is cumbersome and, thus, ineffective and wasteful of time.
It is, therefore, an object of the present invention to provide an apparatus which can be easily used by telephone personnel to access and/or test cable pairs at the main distributing frame of a telephone central office.
It is a further object of the present invention to provide an apparatus meeting the aforesaid objective and which is also of relatively simple construction.